Electrostatic precipitator



April 1, 1952 H. CARLSON 2,591,404

ELECTROSTATIC PRECIPITATOR Filed Nov. 22, 1950 a Sheets-Sheet 1 INVENTOR.

L eonard H. Car/5 April 1, 1952 L. H. CARLSON 2,591,404

ELECTROSTATIC PRECIPITATOR Filed Nov. 22, 1950 8 Sheets-Sheet 2 40rmrd H. Car/Joly WJ M April 1, 1952 L, H, ARLSON 2,591,404

ELECTROSTATIC PRECIPITA'IOR Filed Nov. 22, 1950 8 Sheefcs$heet 3 I N V EN TOR.

Aeqnaru H Car/J01? Mane April 1, 1952 Filed Nov. 22, 1950 L. H. CARLSON ELECTROSTATIC PRECIPITATOR 8 Sheets-Sheet 5 f/vvsuroQ Leonard A Car/Jory April 1, 1952 L. H. CARLSON ELECTROSTATIC PRECIPITATOR 8 Sheets-Sheet 6 Filed NOV, 22, 1950 V INVENTOR.

Zea land H. Car/so April 1, 1952 L. H. CARLSON ELECTROSTATIC PRECIPITATOR 8 Sheets-Sheet '7" Filed NOV. 22, 1950 INVENTOR. 4 ear/ wd H. Car/son BY April 1, 1952 L. H. CARLSON 2,591,404

ELECTROSTATIC PRECIPITATOR Filed Nov. 22, 1950 8 Sheets-Sheet 8 WATER VA 1. vs

JoLEA o/a 9.3

. INVENTOR; Zeormrd Car/6 H BY M (7. PM

fl farney Patented Apr. 1, 1952 UNITED STATES PATENT OFFICE ELECTROSTATIC PRECIPITATOR Leonard H. Carlson, Braintree, Mass., assignor to Westinghouse Electric Corporation, East'Pittsburgh, Pa., a corporation of Pennsylvania Application November 22, 1950, Serial No. 197,066

orderto avoid taking such a precipitator out of service for periodic cleaning, it is proposed that only one vertical row at a time of precipitator units in such a precipitator, be taken out of service and its electrodes cleaned, while the remainder of the precipitator units remain in service.

In'one embodiment of this invention, an electrostatic precipitator has a number of similar precipitator units stacked in vertical and horizontal rows, with electrode cleaning means comprising an upstream box extending vertically from the top to the bottom of the precipitator, and having a width equal to that of a precipitator unit, and a similar downstream box aligned with the upstream box. a Each box contains a vertically extending spray header having spaced water and adhesive spray nozzles, the headers being movable horizontally within the boxes by chain and sprocket mechanisms.

Since in order to conserve space, the boxes will be aligned with one vertical row of units, where no cleaning is going on, they are equipped with doors which when open, permit air to flow through the boxes.

The upstream box acts as a damper closing the inlets of the vertical row of units with which it is aligned when its doors are closed, and its spray nozzles are directed to spray liquid downstream onto the upstream, sides of the ionizer and collector electrodes.

The downstream box acts as a damper closing the outlets of the vertical row of units with which it is aligned when its doors are closed, and its spray nozzles are directed to spray liquid upstream between the collector plates at the downstream sides thereof.

The two boxes are movable with their doors c1osed,horizontally as a unit by chains driven by a crank rotated by an operator. An indicator pointer will show the approximate location of theboxes and when they are in alignment with a vertical row of precipitator units to be cleaned,-

a light flashes. The operator will thenopen a switch connecting the power supply to the row of units to be cleaned; and will then press a button which starts a timer setting up an auto-' matic sequence of operations including in order: the start of the header moving motor, the opening of the water supply valve, the closing, after about five minutes, of the water supply valve, the provision of a drain period of about twenty minutes, the opening of the adhesive supply valve, the spraying of the adhesive for about thirtyseconds completing the wash cycle. The

timer will then be in its original position and automatically stops timing. The next row of cells maythen be washed in a similar manner.

A feature of this invention is that the spray header is moved from a starting point across the width of a precipitator unit and then back again several times during each spray period, and is rotated about its axis in an arc of a circle in one direction at the start of its movement across the width of a precipitator unit, and is rotated about its axis in an arc of a circle in the opposite direction at the start of its movement back to its starting point, these rotations of the header causing its spray nozzles to spray liquid at an angle to the planes of the collector plates so as to spray liquid angularly against one side of each plate inthe horizontal travel of the header in one direction, and causing its spray nozzles to spray liquid at an opposite angle to the planes of the plates so as to spray liquid angularly against the other side of each plate inits horizontal travel in the opposite direction. .This results not only in more effective spraying of liquid upon the plate surfaces than in the prior spraying arrangements in which the nozzles were fixed and directed to spray into the centers of the spaces between adjacent plates, but re-- sults also in the spraying of liquid upon the downstream sides of the tubular ionizer electrodes which previously has not been accomplished. i

An object of this invention is to provide im: proved apparatus for cleaning electrodes of electrostatic precipitators.

Another object of this invention is to provide improved apparatus for washing of the electrodes of electrostatic precipitators.

Another object of this invention is to provide improved apparatus for the spraying of adhesive ,upon the collector electrodes of electrostatic-precipitators.

The invention will now be described with reference to the drawing, of which:

Fig. 1 is a perspective view of a portion of an electrostatic precipitator embodying this invention;

Fig. 2 is an end elevation showing a vertically extending row of precipitator units, and the up stream and downstream washer boxes aligned with the units for washing same, a portion of a side of one of the units being removed for i1- lustrating the ionizer electrodes.

Fig. 3 is an end elevation with portions removed, of one of the washer boxes of the precipitator;

Fig. 4 is a side elevation looking at the door containing side of the box of Fig. 3;

Fig. 5 is a side elevation looking at the open side of the box of Fig. 3, the side opposite that shown by Fig. 4; 'i

Fig. 6 is an enlarged, end elevation of the box with one of its end walls removed for illustrating the components within the box;

Fig. 7 is an enlarged partial end of the header within the box, and of the mechanism for rotating the header; u

Fig. 8 is a sectional view along the lines 88 of Fig.7; r

Fig. 9 is a sectional view along the lines 9-9 of Fig. 7;

Fig. 10 is a partial sectional view showing the seal at the inner-edges of the doors of the box when the doors are closed;

Fig. 11 is a circuit schematic of the control system used, and

Fig. 12 is an enlarged view, in section, illustrating a gas seal between a box and a precipitator unit with which it is aligned.

The electrostatic precipitator consists of a plurality of collecter cells [5 of the type illustrated in detail in the Earl L. Richardson application. Serial No. 757,785, 'filed June 28, 1947 (now Patent 2,535,696, dated December'26, 1950), arranged in vertical and horizontal rows. An ionizer assembly consisting of the frame 16 containing the insulatedly supported ionizer wires l1 and the grounded, tubular electrodes i8 is supported at the upstream side of each cell. For the purpose of description, a collector cell and its associated ionizer assembly is referred to as a precipitator unit.

As is known, it is the practice to spraythe col-.

lector plates of such cells with an. adhesive for aiding the plates to retain the dust electrostatically deposited thereon, the plates being. periodically washed with water for removing the deposited matter and then resprayedwith adhesive.

The invention provides that eachvertical row.

walls 23 at the ends of each row of units, and

have the horizontal resilient seals 8 I at the ends of the seals 8|, forming therewith air seals around the air inlets and outlets of a vertical row of units. The boxes have doors 25 and 26 which when closed, seal the upstream and downstream sides of the vertical row of units with which they are aligned, for preventing the passage of air therethrough, and the escape of spraydroplets 4 therefrom, and when opened, permit free passage of air through the units with which they are aligned.

The end walls 23 of the units contact and together form vertical casing walls at the opposite sides of each' vertical row of units. The tops and bottoms of the units are open for the drainage of liquid, and their fronts and backs are open and are inlets and outlets respectively, for the passage of the air being cleaned.

' The boxes 20 and 2| are supported at their lower ends by the V-grooved rollers 21 on the inverted angles 28 acting as rails at the base of the precipitator. They have the rollers 29 on their upper ends which contact the opposite sides of the vertical guide rail 3| which is one wall of the channel 32.

The chain 33 on the sprockets 34 at one end of the precipitator, and on similar sprockets which are not illustrated, at the other end of the precipitator, are connected at 35 to the boxes; and through the sprockets 36 and 31 and the chain 38 to the crankarm 39 so that when the latter is rotated by an operator, the boxes are movable horizontally on the rollers 21 so as to be positioned in alignment with any of the vertical rows of units.

The doors 25 and 26 are on the upstream side of the upstream box 20, and on the downstream side of the downstream box 2|. Two pairs of doors are provided on each box because due to the extreme height thereof, one set of sheet metal doors would be difficult to maintain in alignment. The doors are connected to the leaf springs 40 and 4| which are attached to the vertically exlarge sprockets 61.

the tubing 5| and the hose 52 to an adhesive The upper end of the header is attached by the angle 54 to the V-grooved roller 55 which rides on the horizontally extending rail 56. The low- 7 er end of the header has the vertically extending roller 51 thereon which is between and contacts the two horizontal guide rails 58.

Eachheader-has attached thereto adjacent its upper and lower ends, the spaced bars 59 in which are keyed the pins 60. Each pin 60 is attached to the block 6| which in turn, is attached by the angles 62 and the pin 63 to the chain 64. The

axis of the pin extends horizontally and is coin-.-

cident with the longitudinal axis of the block 6|. The angles 62 however, are so arranged that while their common axis is perpendicular'to the chain, it is at an angle of about 10 to the longitudinal axis of the block Bi and the axis of the pin 60. 4

Each chain 64 extends over the small sprockets 66 which are mounted on the shafts of the The single chain 68 is meshed with all of the sprockets 61 for simultaneous rotation thereof. The shaft-of one of the sprockets'fi'l has a sprocket 10 attached thereto, external the box and which is meshed with the chain H, which in turn, is meshed with the- The header has the spaced wa'-' sprocket l2 connected by thegearbox "to the electricmotorll'.

Rotation of thesprocket '12 by the motor 14 causes'the chain Hzto 'rotatethe sprocket I0, and through the sprockets 51 and :thechain 68, the sprockets B6 to be rotated. The rdaation of the latter sprockets causes rotation of the chain 64, the upper horizontal passes andthe lowerlhorizontal passes of which move in opposite direction.

Theblocks 6| whichare atta'chedto the chains 64 ride around the end sprockets 66. Due to the angular positions of the pins 60, the headers 46 are rotated 10 to one side-of a plane parallel the planesof thecollector platesof the'units [5, on the upper passes of .the chains as illustrated by Fig. .8 of the drawing, and :are rotated 10 to the other side of such a plane on the lower passes of the chain, as illustrated by .Fig. 9 of the drawing. This causes liquid to be sprayed from the nozzles on theheaders angularly first against the collector plates on one side thereof, and then angularly against the plates on the other side thereofyensuringmore effective wash ing than when the centers of the sprays are directed midway between the plates by fixed spray nozzles as has been the practice in the past. The sprays from the upstream spray nozzles also strike the entire downstream surface of each ionizer tube. This has not been accomplished in prior washers.

As illustrated by Fig. l2, thedownstream ends of the vertical walls 22 of the upstream box, and the upstream ends of the vertical walls 22 of the downstream box, have attached thereto the metal clips 80 in which are clamped the seals 8| of resilient material such as rubber. The upstream and downstream ends of the vertical walls 23 of the precipitator units have the outwardly turned portionsBZ which are heldlin the channel clamp 83. The clamp 83 has the channel 84 attached thereto and which has the vertical sides 85. When the boxes are in alignment with a vertical row of precipitator units, the seals 8| on the opposite sides of the boxes contact the channels 84 between their sides 85. When moving from alignment with one vertical row of units into alignment with another row, the seals 8| slip over the sides 85 of the channels 84. Similar seals 8| in the clips 80 extend horizontally from the boxes at the upper and lower ends of the seals 80.

Fig. 2 illustrates the drain passages 95 for the water draining from the precipitator units, the water draining to a sewer since there is no recirculation.

In operation, when it is decided that a vertical row of units should be cleaned, an operator rotates the crank 39 to align the boxes and 2! with the selected row, at which time the cam 86 on one of the channels 32 (Figs. 2 and 11) strikes the switch arm 81 and closes the switch 88 causing the signal 89 which may be a light, to be energized, indicating exact alignment has been accomplished.

The operator then closes the doors of the boxes and deenergizes the high voltage supply to the precipitator electrodes of the row of units to be washed. He then presses the control button 90 (Fig. 11) which energizes the timer 9| which after about thirty seconds starts timing and first energizes the header moving motor 14. The solenoid 93 which opens the water supply valve is then energized and holds the valve open for about five minutes. During this five minute period, the motor 14 moves the header back and forth so that water is sprayed from the water a, nozzles 43 upon the precipitator electrodes. At the end of the five minute period, the timer closes the valve. After a two minute draining period, thetimer starts the adhesivepump motor which runs for thirty seconds and then is stopped by the timer. The timer is then in its original position and stops timing, stopping the header motor 14 at this time.

The operator then re-applies high voltage to the electrodes of .the row of precipitator units, and if .no more units are to be cleaned, opens the doors of the boxes. If an additional row of units is to be cleaned, the doors of the boxes arenot opened and the boxes are'moved in alignment with the next row of units to be cleaned. The high voltagesupply to the electrodes is disconnected and the button is again depressed,

repeating the sequence of operations controlled by the timer described in the foregoing.

Each vertical row of units can be said to have aseparate casing comprising the end walls 23, the top of the common casing for all of the units, and the concrete foundation shown by Fig. 2, forming a common base for all of the units. Thus each vertical row can be cleaned without affecting the operation of the other rows.

While one embodiment of the invention has been described for the purpose of illustration, it should be understood that the invention is not limited to the exact apparatus and arrangement of apparatus illustrated, since modifications thereof may be suggested by those skilled in the art without departure from the essence of the invention.

What I claim asrny invention, is:

1. An electrostatic precipitator comprising a first casing having a gas inlet and a gas outlet, a precipitator unit in said casing, a washer box aligned with said casing at said inlet and having gas sealing means contacting said casing around said inlet, a vertically extending liquid header in said box, spray nozzles on said header directed to spray liquid downstream with respect to gas flow on said unit, means for moving said header horizontally across said inlet, a second casing having a gas inlet and a gas outlet, in horizontal alignment with said first casing, a precipitator unit in said second casing, and means for moving said box from alignment with said first easing into alignment with said second casing.

2. An electrostatic precipitator as claimed in claim 1 in which the box has a gas inlet and a gas outlet, and has doors for opening and closing said last mentioned inlet.

3. An electrostatic precipitator comprising a first casing having a gas inlet and a gas outlet, a precipitator unit in said casing, a washer box aligned with said casing at said outlet, and having sealing means contacting said casing around said outlet, a vertically extending liquid header in said box, spray nozzles on said header directed to spray liquid upstream with respect to gas flow on said unit, means for moving said header horizontally across said outlet, a second casing having a gas inlet and a gas outlet, in horizontal alignment with said first casing, a precipitator unit in said second casing, and means for moving said box from alignment with said first casing into alignment with said second casing.

4. An electrostatic precipitator as claimed in claim 3 in which the box has a gas inlet and a gas outlet, and has doors for opening and closing said last mentioned outlet.

5. An electrostatic precipitator comprising a first casing having a gas inlet and a gas outlet,

a precipitator unit in said casing, a first washer box aligned with said casing at said inlet and having gas sealing means contacting said casing around said inlet, a liquid header in said box, spray nozzles on said header for spraying liquid downstream with respect to gas flow on said unit, means for moving said header across said inlet, a second washer box aligned with said casing at said outlet and having sealing means contacting said casing around said outlet, a second liquid header in said second box, spray nozzles on said second header, for spraying liquid upstream on said unit, means for moving said second header across said outlet, a second casing having a gas inlet and outlet, a precipitator unit in said second casing, and means for simultaneously moving said boxes from alignment with said first easing into alignment with said second casing.

6. An electrostatic precipitator as claimed in claim in which the first box has a gas inlet and outlet with doors for opening and closing its gas inlet, and the second box has a gas inlet and outlet with doors for opening and closing its gas outlet.

7. An electrostatic precipitator as claimed in claim 1 in which the means for moving the header, moves it in a first pass from a starting point across the inlet, and in a second pass back to the starting'point, and means is provided for rotating the header about its axis in an arc of a circle to one side of a mid-position on the start of its first pass, and for rotating the header about its axis in an arc of a circle to the other side of the mid-position on the start of the second pass.

8. An electrostatic precipitator as claimed in claim 7 in which the box has a gas inlet and a gas outlet, and has doors for opening and closing said last mentioned inlet.

9. An electrostatic precipitator as claimed in claim 3 in which the means for moving the header, moves it in a first pass from a starting point across the outlet, and in a second pass back to the starting point, and means is provided for rotating the ieader about its axis in an arc of a circle to one side of a mid-position on the start of the first pass, and for rotating the header about its axis in an arc of a circle to the other side of the mid-position on the start of the second pass.

10. An electrostatic precipitator as claimed in claim 9 in which the box has a gas inlet and a gas outlet, and has doors for opening and closing saidlast mentioned outlet.

11. An electrostatic precipitator as claimed in claim 5 in which the means for moving each header moves it in a first pass from a starting point at one side of the box in which it is arranged, across the box in which it is arranged, to the other side thereof, and ma second pass back to the starting point, and. means is provided for rotating each header about its axis in an arc of a circle to one side of a mid-position on the start of its first pass, and in an arc of a circle to the other side of its mid-position on the start of its second pass.

LEONARD I-I. CARLSON.

REFERENCES CITED The following references are of record in the file of this patent: 1

'U'NITEn STATES arms 

